A plan by state transportation officials to begin more than $15 billion in improvements to the existing Amtrak system is appropriate because it can serve as a bridge to the more expensive high-speed rail system, scheduled to begin construction this summer.

A large portion of those improvements are slated for the San Joaquin Valley, and likely will offer a glimpse of what passenger rail service will look like once the high-speed rail system is in place. Figures for Amtrak and passenger rail service on the San Joaquin line -- from Bakersfield to Sacramento -- indicate that ridership in the valley is increasing, a welcome sign for supporters of high-speed rail.

In the last three months of 2012, San Joaquin trains, already among Amtrak's busiest, carried almost 400,000 riders, an increase of about 11 percent from the same period the prior year. The new plan will pump more than $500 million in upgrades to the valley corridor in the next five years, and about $1.7 billion over the next two decades. Initial improvements will be to tracks, signal systems and stations. It'll be a preview of sorts, too.

In addition to offering more trains and routes, the improvements can show an increase in train speed from the average of 53 mph for the Bakersfield-to-Sacramento corridor to about 125 mph. That's a far cry from 220-mph bullet trains, but it should dramatically improve service and travel times until then.

Phasing in portions of HSR as it moves toward reality is a prudent approach.